Thursday, February 17, 2011

February 13 - Winter Songbird Monitoring

There are not too many places in Canada where you have the opportunity to see, let alone band warblers in winter. Yellow-rumped and Townsend's Warblers regularly winter in small numbers in the Lower Mainland and on Vancouver Island. Wintering locations are most likely limited by temperature and food supply. Townsend's Warblers have been found to use backyard suet feeders, however Yellow-rumped Warblers feed on a more natural mix of insects and berries. As a result Yellow-rumps are found more frequently found in coastal areas, where temperatures are more moderate and insects can usually be found throughout the winter. Iona Island is one of the few locations where Yellow-rumps have been found reliably in winter. This is likely because of the moderating influence of the ocean and the relative abundance of flying insects around both the sewage lagoons and wetlands.

This winter up to eight have been found at Iona and all look to be adult males, with an equal split of Myrtle and Audubon's subspecies. At least one or two have been teasing us all winter by flying just above the nets. Recently, though, the entire flock has been spending more time near the nets in the willows at the edge of the woodlot. Possibly as a result of this, at our last monitoring session we finally caught one!

The bird was an after second-year male Myrtle Warbler. It will be interesting to see now that the flock is spending more time around the nets if more will be caught, and if they will return next year. Other interesting birds around included a recapture Varied Thrush (originally banded in late November), a Spotted Towhee (last seen in April), and a Cackling Goose in the sewage lagoons.

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